Looks like 1000 RPM per volt.Just in case some do not know the more winds a motor has the slower it will spin.But the more torque it will have.The lower the turns it has the faster it will spin.But it will have less torque. BD.

The Graupner range of brushed motors are well documented, probably one of the reasons for their popularity. I use the rev counter on my Eagletree logger to measure RPM on motors of unknown origin, a very useful gadget to have.6K is much too high for these propulsors, and the motor will pull a lot of amps. 2:1 gearing/belts and it will be spot-on assuming you're happy running a 6volt electrical system.

Robbe now do some modestly sized outrunners with very low KV outrunners, specifically designed for direct drive on large marine props. They do one wound for 300kv, and another for 500kv, designed for 60mm and 50mm diameter props respectively.

True enough.I just don't like fiddeling with gear or belt reductions if I don't have to.The 60 turn Venom will spin the PJ with no problem and a little extra for a rainy day.The stick on the left called a throttle does not have to be pushed to the limit and you should be able to cruse very well with less than 1/2 stick.But that extra power is there if you feel the need!! The need for speed!! We are just giving you different options Wayne. You can't say any of them are right or wrong but all will work. BD.

I have made my move. I told Mike to make up a 3.5-1 belt drive to go to my special little 500 12 volt motor. Like some things, get as close as you can, and go for it. My guess is it will easily do scale speeds for extended period of time, and overtake an Ohio in the baffles, if needed... Yall want a build thread? It will take a while. But you are not in a hurry,are you?

I have it already. Go to build threads and find the x-tail akula, or 4th gen akula, I forget which. You will see the pumpjet I had for that project. I kept a spare. Putting it against the plans I had made up, it is perfect, size wise. I took a 1/96 Seawolf pumpjet, and modified it to look more like the Alorosa pumpjet. From all I have seen so far, I may be correct on the Borei pumpjet as well. It was a good guess on what I call "tendencys" by the Russsians.

So you're using one of Dave Merriman's Seawolf propulsors, okay cool. Looks like a pre-swirl pumpjet on the plan, but that could be guesswork. That combination should work well then, Dave tends to go for a more modest pitch on the blades than Prop Shop. If it had been the latter, I would have said 4 or 5:1 gearing as these props are very high in pitch and need a lot of power to push them past 2000 RPM.

It is not David's. It is Pete P's. Who was kind enough to indulge me with this. I could not have done it without him, for sure. Look at the Alorsa pump jet pics, then look at the wrap around the Borei. The "tail" of both of them has the hole in the middle of a rounded tip to collapse bubbles.Just another approach to the same ends.. Stealth.

There are several 500 size motors, but here is the deal. Look close at the specs of the 500E 12 volt. Low amp, slower turning. That looks like the 500 motor (if that is the size you need). Compare it to the other 500s. It looks like the 500 one would need.

Now, here is a catch. I can not find anyone else who carrys that motor. There might be another source out there, but it is not easy to find. They are cheap. I already have one for the X tail Akula, and one for the Borei. Before I posted this, I ordered enough motors I will not have to worry about locating any more for any future projects (like a typhoon, Mike class, etc), or replacement. Now you can wipe out their inventory if you want to